ADHD Diagnostic Criteria

DSM-5-TR lists nine inattention symptoms and nine hyperactivity-impulsivity symptoms. Children under 17 need at least six symptoms in a domain; people aged 17 and over need at least five. Symptoms must have persisted for at least six months to a degree that is inconsistent with developmental level.

Counting symptoms is only one part. The criteria also require that several symptoms were present before age 12, that they occur in two or more settings (for example home, school, work or relationships), that there is clear evidence they interfere with or reduce the quality of functioning, and that they are not better explained by another mental health condition.

ICD-11 (code 6A05) describes the same core features — a persistent pattern of inattention and/or hyperactivity-impulsivity with onset during the developmental period, typically early to mid-childhood, that directly affects academic, occupational or social functioning. ICD-11 does not set exact symptom counts; it relies more on clinical judgement.

Criteria are not a checklist a patient completes. A clinician gathers developmental history, current symptoms, examples of impairment and, where possible, information from someone who knew you as a child. Structured interviews such as DIVA-5 help ensure every criterion is explored systematically.

NICE NG87 is clear that a diagnosis should not be made on the basis of rating scales or observation alone. The clinician also has to consider other explanations — anxiety, depression, sleep problems, trauma, autism, substance use or physical health conditions — that can look similar.